hhea - Horizontal Header (OpenType 1.7)

This table contains information for horizontal layout. The values in the minRightSidebearing, minLeftSideBearing and xMaxExtent should be computed using only glyphs that have contours. Glyphs with no contours should be ignored for the purposes of these calculations. All reserved areas must be set to 0.

Type	Name	Description
Fixed	Table version number	0x00010000 for version 1.0.
FWORD	Ascender	Typographic ascent. (Distance from baseline of highest ascender)
FWORD	Descender	Typographic descent. (Distance from baseline of lowest descender)
FWORD	LineGap	Typographic line gap. Negative LineGap values are treated as zero in Windows 3.1, System 6, and System 7.
UFWORD	advanceWidthMax	Maximum advance width value in 'hmtx' table.
FWORD	minLeftSideBearing	Minimum left sidebearing value in 'hmtx' table.
FWORD	minRightSideBearing	Minimum right sidebearing value; calculated as Min(aw - lsb - (xMax - xMin)).
FWORD	xMaxExtent	Max(lsb + (xMax - xMin)).
SHORT	caretSlopeRise	Used to calculate the slope of the cursor (rise/run); 1 for vertical.
SHORT	caretSlopeRun	0 for vertical.
SHORT	caretOffset	The amount by which a slanted highlight on a glyph needs to be shifted to produce the best appearance. Set to 0 for non-slanted fonts
SHORT	(reserved)	set to 0
SHORT	(reserved)	set to 0
SHORT	(reserved)	set to 0
SHORT	(reserved)	set to 0
SHORT	metricDataFormat	0 for current format.
USHORT	numberOfHMetrics	Number of hMetric entries in 'hmtx' table

NOTE: The ascender, descender and linegap values in this table are Apple specific. Also see information in the OS/2 table.